[invalidations] Convert invalidations to use TreeOutline

Source/devtools/front_end/timeline/invalidationsTree.css

Index: Source/devtools/front_end/timeline/invalidationsTree.css
diff --git a/Source/devtools/front_end/timeline/invalidationsTree.css b/Source/devtools/front_end/timeline/invalidationsTree.css
new file mode 100644
index 0000000000000000000000000000000000000000..98d5004cf1fd4ebdd457781ef4069c40bb9d0ec6
--- /dev/null
+++ b/Source/devtools/front_end/timeline/invalidationsTree.css
@@ -0,0 +1,28 @@
+/*
+ * Copyright 2015 The Chromium Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+.header, .children, .content {
+    min-height: initial;
+    line-height: initial;
+}
+
+/* This TreeElement is always expanded and has no arrow.   */
+/* FIXME(crbug.com/475618): Implement this in TreeElement. */
+.children li::before {
+    display: none;
+}
+
+.content {
+    margin-bottom: 4px;
+}
+
+.content .stack-preview-container {
+    margin-left: 8px;
+}
+
+.content .node-list {
+    margin-left: 10px;
+}